marking pcb's

Dallas Semiconductors (now owned by Maxim) used to make a part in small two pin package that contained a unique 64 bit serial number (eg every one is different). I think it was the DS2400 and they were intended for applications like MAC addresses on NIC's.

One of these epoxied into a hole in the PCB would be impossible to remove and replace without damage.

The nearest I could find on the Maxim web site now are these ibuttons which are a bit too big I think but perhaps I didn't look hard enough.

formatting link

into

casually

projects

Reply to
CWatters
Loading thread data ...

The original was the DS2400. The silicon designs have been tweaked by DalSemi to fix a few glitches in the 1-Wire driver. The new part number (when I say "new" I mean "since 1996-ish") is DS2401. ISTR there's even a Chipscale version - solder some really tiny wire to it and embed it in hole on the board. Add some Araldite and you've got a usable anti-tamper method. You'd need a 1-Wire reader (a DS9097U and a Blue Dot Receptor) to read the codes, though. Keep a database using Access or Excel (or whatever) - use the 1-Wire Viewer to read the code off the chip, then look it up in your database.

Later.

--
Phil.                                | Acorn RiscPC600 Mk3, SA202, 64MB, 6GB,
philpem@despammed.com (valid address)| ViewFinder, 10BaseT Ethernet, 2-slice,
 Click to see the full signature
Reply to
Philip Pemberton

The post was a bit vague.....I don't see anywhere the claim that the boards are the same......I guess you have insider info since you find it necesary to correct..... Though, you might be correct!!

Reply to
Ross Mac

Only one problem....once you rout the board from it's frame...the notches are gone.....I have seen this time and time again when engineers are running tests.....You would have to notch the finished product....and most probably make it seriously ugly.....

Reply to
Ross Mac

On Wed, 17 Dec 2003 03:11:30 -0500, "zapp" Gave us:

Use the opaque epoxy as an ink. Make numerals. It can be scraped off, but where do they get *YOUR* brand to remark it with?

Since the notches do not involve any actual numerals, but are encoded by you with a limited set, they cannot decode them to copy or falsify them.

Reply to
DarkMatter

into

casually

projects

Now we know they are all the same!....here is an easy way to identify each board....during the drilling process have a serial number drilled with one of the smaller holes in a land area....there are M codes that allow you to do this and it is a minimal engineering expense....it could be as easy as 1 to 50 ...they could easily do this for you...and hey, you can't forge that now can you.....Just assign a number to each student.....You may have seen card frames with lot numbers drilled into them...this is how some PCB houses keep board lots from getting mixed during the plating process where most of the "evils" occur..... A happy holiday season to all.....Ross

Reply to
Ross Mac

On Wed, 17 Dec 2003 11:11:32 GMT, "CWatters" Gave us:

They also have some with RTCs in them. The startup time, and serial cannot be duped, so hiding it physically is not required.

There are RTC chips out there that are serialized.

formatting link

Reply to
DarkMatter

On Thu, 18 Dec 2003 02:23:08 GMT, "Ross Mac" Gave us:

It was obvious to me. It was later confirmed by the instructor.

Reply to
DarkMatter

On Thu, 18 Dec 2003 02:26:16 GMT, "Ross Mac" Gave us:

I guess that you've never owned or used needle files.

Small triangular notch, less than a half mm deep. Almost any encoding schema can be used, and one can even be made up.

All but crack proof. Colored fingernail polish can even be introduced, and the finished work varnished over to seal it in.

Nice, pleasing to the eye view of the individual PCB encoding.

The boards are already built as far as the SMT reflow part goes, if it is SMT at all. No frame involved. They are all already broken out, and get worked on individually by the students.

Notches?... We need some stinkin' notches!...

Badges?... We don' need no stinkin' badges!...

Reply to
DarkMatter

boards

necesary

Glad you're sportin' wood on this one.....He never stated it until late in the post!

Reply to
Ross Mac

On Thu, 18 Dec 2003 02:33:13 GMT, "Ross Mac" Gave us:

The boards are already made, and even if they weren't, they would still have to all be the same for each PCB on the palletized "frame"

Going through all of that trouble is kaka. Hell, the easiest way would be to have them laser marked after the PCB mfg part was finished. 3 seconds per PCB... max.

Kee rimany!

Reply to
DarkMatter

each

one

to

1

that

seen

houses

of

No trouble at all.....what is your experience in this field???

Reply to
Ross Mac

What is then to prevent another student from sabotaging the serial on others' boards?

Reply to
Kevin G. Rhoads

I

Get yourself a invisable marking pen that shows up under UV light. They are used for secrectly marking things for what ever purpose you have. Probably available at your local office supply store....Paul

Reply to
PJ

On Thu, 18 Dec 2003 15:07:29 -0500, "Kevin G. Rhoads" Gave us:

The other students... and their guns. :-]

Reply to
DarkMatter

On Thu, 18 Dec 2003 17:36:51 -0800, "PJ" Gave us:

With as many UV sources in school labs, I'd think that it would get found out.

Reply to
DarkMatter

How are you going to keep it from washing away when the flux is cleaned off the board?

--
7 days!


Michael A. Terrell
 Click to see the full signature
Reply to
Michael A. Terrell

message

running

probably

Nice snip job!

Reply to
Ross Mac

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.